Developmental Projects

In addition to providing services, the Model Systems Core is actively working to develop new PKD-related technologies in C. elegans, rodents and zebrafish.

C. elegans

The core is currently performing a whole-genome genetic screen to search for both suppressors and enhancers in the polycystin signaling pathway. All mutants, including those eliminated from this screening, will be available to Mayo and non-Mayo investigators.

Additionally, the core is investigating small-scale or targeted small-molecule screening to identify drugs that can suppress or enhance polycystin function — especially for the molecules targeting PKD2 channel activity — or their downstream signaling. Finally, the core is looking at using in vitro primary cultured worm neuron cells expressing polycystins to study the electrophysiological properties of polycystin complex in their native environment.

Rodents

Pkhd1lsl(-)/lsl(-) mouse: This recently generated mouse has a Cre removable transcriptional STOP cassette in intron-2 of the PKHD1 gene, is unable to make PKHD1 mRNA and is null for fibrocystin protein. It develops liver cysts by one month of age, which progress to involve the entire liver by nine months. In the kidney, only the females develop proximal tubular dilatation (beginning at three months of age).

Pkhd1Pk(+)/Pk(+) mouse: This recently generated mouse has two SV5-Pk epitope tags inserted in tandem into exon-3 of the endogenous PKHD1 gene. These tags are immediately C-terminal of the signal peptide of mouse fibrocystin, so that once the protein is processed in the endoplasmic reticulum, the two tags are at the extreme N-terminus of the mature protein — an ideal location to study processing, secretion, location and glycosylation. The animal is phenotypically normal and never develops cysts.

Pkd1 R3277C hypomorphic mouse model: This is a knock-in mouse model carrying the PKD1 R3277C hypomorphic allele. After complete characterization of the homozygous mice, this model will be well-suited to test possible therapies in an animal model of PKD1 disease.

Lastly, a central developmental objective in the core is to develop a tetracycline-inducible system for the proximal, distal and collecting tubules of the kidney and the biliary tree of the liver. This would allow the core to induce molecules in these tissues and "switch on" transgenes in a temporal- and tissue-specific way.

Zebrafish

A number of developmental technologies are being investigated in Mayo’s Zebrafish Core Facility, all of which will benefit the Model Systems Core and its users. These include:

  • Custom zinc finger nucleases for targeted gene knockdown
  • Generation of a panel of 2,500 molecularly tagged and cryopreserved protein trap lines of conditional insertional gene-break transposon zebrafish lines
  • Small-molecule screening for in vivo new or combination drug testing in a preclinical animal model